Method for early detection and anticipatory control of consumer-end load shedding in an electrical grid, and apparatus for carrying out the method

Abstract

A method for early detection and anticipatory control of consumer-end load shedding in a single-phase or polyphase electrical grid supplied with single phase or polyphase by at least one generator driven by at least one rotating machine includes measuring a current and a voltage between the at least one generator and the electrical grid and/or a current and a voltage in the electrical grid, deriving at least one signal from the measured current and voltage and using the at least one derived signal to act on the at least one rotating machine.

What is claimed is: 
     
       1. A method for early detection and anticipatory control of consumer-end load shedding in a single-phase or polyphase electrical grid supplied with single phase or polyphase by at least one generator driven by at least one rotating machine, the method comprising:
 measuring a current and a voltage, the current and the voltage being measured between the at least one generator and the electrical grid, in the electrical grid or at both locations; 
 deriving at least one signal from the measured current and voltage; 
 using the at least one derived signal and a gradient signal generated from the at least one derived signal to at least partially reduce a load on the at least one rotating machine, 
 wherein the at least one derived signal and the gradient signal are sent to a regulator of emitted power of the at least one rotating machine so as to influence a power output of the at least one rotating machine during a load shedding in the grid; and 
 subsequently matching a generation of and demand for electric power. 
 
     
     
       2. The method as recited in  claim 1 , wherein at least partially reducing the load includes controlling a power output of the at least one rotating machine using an actuator connected to the regulator, wherein the at least one rotating machine is a turbine. 
     
     
       3. The method as recited in  claim 2 , wherein the turbine is a steam turbine, and wherein the controlling includes controlling a supply of steam to the turbine. 
     
     
       4. The method as recited in  claim 2 , wherein the turbine is part of a gas turbine, and wherein the controlling includes controlling a supply of at least one of fuel and combustion air to the gas turbine. 
     
     
       5. The method as recited in  claim 2 , further comprising amplifying the at least one derived signal in an output stage before the at least one derived signal is sent to the regulator. 
     
     
       6. A method for early detection and anticipatory control of consumer-end load shedding in a single-phase or polyphase electrical grid supplied with single phase or polyphase by at least one generator driven by at least one rotating machine, the method comprising:
 measuring a current and a voltage, the current and the voltage being measured between the at least one generator and the electrical grid, in the electrical grid or at both locations; 
 deriving at least one electrical variable from the measured current and the measured voltage; 
 calculating a rate of change of the at least one electrical variable; and 
 using the at least one derived electrical variable and the rate of change of the at least one electrical variable to at least partially reduce a load on the at least one rotating machine, 
 wherein the at least one derived signal is used as soon as the calculated rate of change overshoots or undershoots a threshold value. 
 
     
     
       7. The method as recited in  claim 6 , wherein the at least one electrical variable includes at least one of a real power, a real current and a reactive power and a reactive current, and wherein the calculated rate of change includes at least one of a real power gradient, a real current gradient, a reactive current gradient, a reactive power gradient and a rotation speed gradient. 
     
     
       8. The method as recited in  claim 7 , further comprising computing a plurality of threshold value signals by comparing a calculated rate of change of at least one of one of the reactive current and the reactive power with a respective threshold value; and wherein the deriving the at least one signal is performed by logically linking the plurality of threshold signals to one another in an evaluation unit based on a structure of the electrical grid. 
     
     
       9. A method for early detection and anticipatory control of consumer-end load shedding in a single-phase or polyphase electrical grid supplied with single phase or polyphase by at least one generator driven by at least one rotating machine, the method comprising:
 measuring a current and a voltage, the current and the voltage being measured between the at least one generator and the electrical grid, in the electrical grid or at both locations; 
 deriving at least one signal from the measured current and voltage; and 
 obtaining at least one electrical variable for the detection of the load shedding and a rotation speed gradient of a rotor of the at least one rotating machine from the measured current and voltage; and 
 using the at least one electrical variable and the rotation speed gradient of the rotor to generate a load reduction signal for controlling the at least one rotating machine. 
 
     
     
       10. The method as recited in  claim 9 , further comprising calculating an expected acceleration from an instantaneous power and a mass moment of inertia of the rotor. 
     
     
       11. A method for early detection and anticipatory control of consumer-end load shedding in a single-phase or polyphase electrical grid supplied with single phase or polyphase by at least one generator driven by a plurality of rotating machines, the method comprising:
 measuring a current and a voltage, the current and the voltage being measured between the at least one generator and the electrical grid, in the electrical grid or at both locations; 
 deriving at least one signal from the measured current and voltage; and 
 using the at least one derived signal and a gradient signal generated from the at least one derived signal to at least partially reduce a load on each of the rotating machines, 
 wherein the plurality of rotating machines are configured to drive a plurality of generators, and 
 wherein the at least one derived signal is used to influence power generated by the plurality of rotating machines in response to a load shedding of the electrical grid.